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Can not read values/nodes from xml using c#

I'm trying to read values from following xml (which is previously fetched from FTP):
<?xml version="1.0" encoding="utf-8"?>
<eventdata xmlns="http://www.demoweb.net/xml/eventdata" >
<site>
<sitelink>demotesting</sitelink>
<user>15101991</user>
<measurement>
<nodelink>012019120312064500</nodelink>
<containername>A1</containername>
<time>2020-04-30T11:25:35</time>
<value type="n_v_unitvalue">0.04</value>
<value type="n_v_unitvalue_diff">0.040</value>
</measurement>
<measurement>
<nodelink>012019120312064501</nodelink>
<containername>A2</containername>
<time>2020-04-30T11:25:35</time>
<value type="n_v_unitvalue">0.0</value>
<value type="n_v_unitvalue_diff">-0.001</value>
</measurement>
<measurement>
<nodelink>012019120312064502</nodelink>
<containername>A3</containername>
<time>2020-04-30T11:25:34</time>
<value type="n_v_unitvalue">0.0</value>
<value type="n_v_unitvalue_diff">0.000</value>
</measurement>
</site>
<createdate>2020-04-30T11:25:35</createdate>
</eventdata>
Before I start, file is sucessfully loaded into memory :)
As you can see root node is eventdata, and site is the node where all data is contained.
So basically I need to loop all measurement nodes and get the data.
I also were struggling to get out user node.. here's what I've tried so far:
using (StreamReader xml_reader = new StreamReader(xml_response.GetResponseStream()))
{
string xml = xml_reader.ReadToEnd();
XmlDocument xmldoc = new XmlDocument();
xmldoc.LoadXml(xml);
XmlNodeList mainFileContent = xmldoc.SelectNodes("eventdata");
// XmlNodeList mainFileContent = xmldoc.SelectNodes("eventdata/site");
XmlElement root = xmldoc.DocumentElement;
if (mainFileContent != null)
{
foreach (XmlNode node in mainFileContent)
{
var user = node["user"].InnerText;
}
}
}
What I'm missing?
THANKS GUYS
CHEERS

Your eventdata node has own xmlns declaration, you should properly handle it using XmlNamespaceManager and select the nodes with x:eventdata/x:site XPath expression
var xmldoc = new XmlDocument();
xmldoc.LoadXml(xml);
var nsmgr = new XmlNamespaceManager(xmldoc.NameTable);
nsmgr.AddNamespace("x", xmldoc.DocumentElement.NamespaceURI);
var mainFileContent = xmldoc.SelectNodes("x:eventdata/x:site", nsmgr);
foreach (XmlNode node in mainFileContent)
{
var user = node["user"]?.InnerText;
}

Use below code to read measurement
using (StreamReader xml_reader = new StreamReader(xml_response.GetResponseStream()))
{
string xml = xml_reader.ReadToEnd();
XmlDocument xmldoc = new XmlDocument();
xmldoc.LoadXml(xml);
var nsmgr = new XmlNamespaceManager(xmldoc.NameTable);
nsmgr.AddNamespace("ns", "http://www.demoweb.net/xml/eventdata");
XmlNodeList mainFileContent = xmldoc.SelectNodes("ns:eventdata/ns:site",nsmgr);
XmlElement root = xmldoc.DocumentElement;
if (mainFileContent != null)
{
foreach (XmlNode site in mainFileContent)
{
var user = site["user"].InnerText;
XmlNodeList measurements = site.SelectNodes("ns:measurement", nsmgr);
if (measurements != null)
{
foreach (XmlNode measurement in measurements)
{
var containername = measurement["containername"].InnerText;
var time = measurement["time"].InnerText;
XmlNodeList values = measurement.SelectNodes("ns:value", nsmgr);
if (values != null)
{
foreach (XmlNode value in values)
{
var type = value.Attributes["type"].Value;
var v2 = value.InnerText;
}
}
}
}
}
}
}

How to update xml file without using Linq?

I have this xml file:
<students>
<student>
<name>Mark</name>
<age>20</age>
</student>
<student>
<name>Adam</name>
<age>32</age>
</student>
I want to change the age of Adam, for that I did:
XmlDocument doc = new XmlDocument();
doc.Load("/path/to/sutdents.xml");
XmlNode n = doc.SelectSingleNode("/students/student[name='" + student.name +
"']");
if (n != null)
{
n.SelectNodes("age").Item(0).FirstChild.Value = new_value;
}
but I get "n" as a null value.
I tried another way to do that by searching for the node using foreach and make change, but I get Null Exception:
XmlDocument doc = new XmlDocument();
doc.Load("/path/to/sutdents.xml");
XmlNodeList nodes = doc.SelectNodes("/students/student");
foreach (XmlNode node in nodes)
{
if (node.FirstChild.InnerText == student.name)
{
node.SelectSingleNode("age").InnerText = new_value;
}
}
what I missing here please?
Thanks in advance

I tried to run your code. that is work! check what is the value of student.name.
XML [sutdents.xml]
<?xml version="1.0" standalone="yes"?>
<students>
<student>
<name>Mark</name>
<age>20</age>
</student>
<student>
<name>Adam</name>
<age>32</age>
</student>
</students>
sample code:
XmlDocument doc = new XmlDocument();
doc.Load("sutdents.xml");
XmlNode n = doc.SelectSingleNode("/students/student[name='Adam']");
if (n != null)
{
n.SelectNodes("age").Item(0).FirstChild.Value = "44";
}
doc.Save("sutdents.xml");

i hope this helps;
When Using foreach:
XmlNodeList studentsList = doc.ChildNodes[0].SelectNodes("student");
foreach (XmlNode node in studentsList)
{
if (node.ChildNodes[0].InnerText == student.name) //name
{
node.ChildNodes[1].InnerText = new_value; //age
}
}

Your Code is Correct here is a screen shot of your debugged code with same xml and mentioned code, check you are passing student.name with correct value and case sensitive.

Try this using XDocument:
private static void UpdateXML(string xmlpath, string studentName, int age)
{
var doc = XDocument.Load(xmlpath);
//Get student
var student = doc.Descendants("student").Where(att => att.Element("name") != null && att.Element("name").Value.Equals(studentName)).FirstOrDefault();
if (student != null)
student.Element("age").Value = age.ToString();
doc.Save(xmlpath);
}

Saving to xml file

I have a question about updating data in current xml file.
For example I want to change Radius to "50"
XML file:
<?xml version="1.0" encoding="utf-8"?>
<Settings>
<Radius>25</Radius>
<Length>40</Length>
<Height>15</Height>
<Name>Oks</Name>
</Settings>
I can read these settings with this code:
public void GetSettings()
{
XmlDocument xml = new XmlDocument();
xml.Load(location);
XmlNodeList xnList = xml.SelectNodes("/Settings");
foreach (XmlNode xn in xnList)
{
tb_height.Text = xn["Height"].InnerText;
tb_lenght.Text = xn["Length"].InnerText;
tb_radius.Text = xn["Radius"].InnerText;
tb_name.Text = xn["Name"].InnerText;
}
}

Not really sure what you are trying to do.
but to save your file, you can simply:
xml.Save(PathToSaveTo);

Got it working with
public void SaveSettings()
{
XmlDocument xml = new XmlDocument();
xml.Load(location);
XmlNodeList xnList = xml.SelectNodes("/Settings");
XmlNode xn = xml.SelectNodes("/Settings").Item(0);
xn["Height"].InnerText = tb_height.Text;
xn["Length"].InnerText = tb_lenght.Text;
xn["Radius"].InnerText = tb_radius.Text;
xn["Name"].InnerText = tb_name.Text;
xml.Save(location);
}

Issue with parser xml

I've this xml :
<?xml version="1.0"?>
<channel>
<item>
<title>Le joyeux médecin</title>
<description>
<p>test blague description</p>
</description>
<pubDate>Dimanche, 02/03/2014</pubDate>
</item>
</channel>
And the code to parse the xml :
private void Feed(object Sender, DownloadStringCompletedEventArgs e)
{
XElement _xml;
try
{
if (!e.Cancelled)
{
_xml = XElement.Parse(e.Result);
Results.Items.Clear();
foreach (XElement value in _xml.Elements("channel").Elements("item"))
{
_item = new Flux();
_item.Title = value.Element("title").Value;
_item.Description = Regex.Replace(value.Element("description").Value,
#"<(.|\n)*?>", String.Empty);
Results.Items.Add(_item);
break;
}
}
}
catch
{
MessageBox.Show(e.Error.Message);
}
}
_xml contains the xml but the code into the foreach doesn't execute and I don't know why... thanks for any help !

Change your loop as:
foreach (XElement value in _xml.Elements("item"))
{
}
Since _xml is already channel

Querying XML document

I am trying to query an xml document, but this code doesn't read xml parts with closed tag notation but reads fine xelement. Can anyone spot what I'm doing wrong?
I have program generated XML document which gives closed tagged file hence its an issue now..
<?xml version="1.0" encoding="utf-8" ?>
<Student>
<Person name="John" city="Auckland" country="NZ" />
<Person>
<Course>GDICT-CN</Course>
<Level>7</Level>
<Credit>120</Credit>
<Date>129971035565221298</Date>
</Person>
<Person>
<Course>GDICT-CN</Course>
<Level>7</Level>
<Credit>120</Credit>
<Date>129971036040828501</Date>
</Person>
</Student>
class Program
{
static void Main(string[] args)
{
XDocument xDoc = XDocument.Load(AppDomain.CurrentDomain.BaseDirectory + "Customers.xml");
IEnumerable<XElement> rows = from row in xDoc.Descendants("Person") select row;
foreach(XElement xEle in rows)
{
IEnumerable<XAttribute>attlist = from att in xEle.DescendantsAndSelf().Attributes() select att;
foreach(XAttribute xatt in attlist)
{
Console.WriteLine(xatt);
}
Console.WriteLine("-------------------------------------------");
}
Console.ReadLine();
}
}

Since you have added Course and other attributes as XElement, so you need to loop on XElements instead of attributes -
foreach (XElement xEle in rows)
{
IEnumerable<XAttribute> attlist = from att in xEle.DescendantsAndSelf()
.Attributes() select att;
foreach (XAttribute xatt in attlist)
{
Console.WriteLine(xatt);
}
foreach (XElement elemnt in xEle.Descendants())
{
Console.WriteLine(elemnt.Value);
}
Console.WriteLine("-------------------------------------------");
}

First you must navigate to Person level and iterate through Persons, then for each Person you can iterate through its attributes.
private static void Main(string[] args)
{
//string path = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
//XDocument xDoc = XDocument.Load(path + "\\Student Data\\data.xml");
XDocument xDoc = XDocument.Load(AppDomain.CurrentDomain.BaseDirectory + "Customers.xml");
IEnumerable<XElement> xElements = xDoc.Descendants("Person");
foreach (XElement element in xElements)
{
foreach (XAttribute attribute in element.Attributes())
{
Console.WriteLine(attribute);
}
Console.WriteLine("-------------------------------------------");
}
Console.ReadLine();
}